The two major areas of continued activity are the relation of genital mycoplasmas to perinatal morbidity and mortality, and the studies of the origin of hypertension in childhood. In addition, a number of related studies have been conducted. With respect to the genital mycoplasmas, intensive studies have continued of the serological characteristics of genital mycoplasmas and the delineation of the nature of the antibody response to these organisms during and immediately after pregnancy. Different types of antibody response, and their probable significance, have been demonstrated. Approximately 50% of pregnant women underwent some significant change in titer of antibody to one or another strain of genital mycoplasma in each pregnancy, suggesting that the effect of genital mycoplasmas on a pregnancy may be greatest in the youngest individuals experiencing the first few pregnancies, at most. Controlled clinical trial of the effect of antimycoplasmal antibiotics on the outcome of pregnancy continues, as previously described. Definitive findings that erythromycin estolate is sufficiently hepatotoxic to lead to its withdrawal from further use has been advanced. Detailed studies of the membrane structure of genital mycoplasmas are now in progress. In relation to the origins of hypertension, it has been demonstrated that the tracking of blood pressure is a phenomenon that is identified in small children, with a correlation between two successive blood pressure measurements, taken 2-4 years apart, of approximately 0.25 in children age 2-4, rising to adult levels of approximately 0.6-0.7 by age 21. Change in body weight has been a significant factor in this increase in tracking correlation. Sib-sib aggregation of blood pressure has been demonstrated before age six months but is not present at birth. Mother-child aggregation of blood pressure is present by the second day of life at levels of r equals 0.17. Urinary kallikrein levels are highest in children with the lowest blood pressure and lowest in children with the highest blood pressure and a consistent racial difference is found in urinary kallikreins, when there is no such difference in blood pressure of children by race. A hypothesis has advanced that urinary kallikrein indicates a precursor state to the later development of differences in blood pressure between the races and that the metabolic alteration leading to the differen (Text Truncated - Exceeds Capacity)